Light rain began falling north of San Francisco on Sunday in what forecasters said was the first sign of a series of storms expected to bring heavy rainfall and snow to drought-parched California this week.
The storm that moved in Sunday morning was expected to pick up strength and cover a larger area of Northern California later in the day, the National Weather Service said.
A second, stronger storm is forecast to arrive Monday night and Tuesday and bring in about a half an inch of rain. That system will be packed with gusty winds and heavier rain, said forecaster Johnny Powell.
Yet another round of rain and gusty winds is expected Wednesday and Thursday, when heavy rain is forecast for the Santa Cruz and Santa Lucia mountain ranges.
"Friday looks like a dry, clear day but more rain is expected Saturday,'' Powell said.
Powell said about 2 feet of fresh snow are expected to fall this week in the Sierra Nevada's highest points.
Meanwhile Southern California is bracing for a series of storms expected to begin late Sunday that could last all week.
The service said persistent rainy conditions could put some Los Angeles County communities at risk of flash flooding with mud and debris flows, especially in wildfire burn areas.